Purification of gonococcal R-type lipopolysaccharide not bearing the lactose-like antigen

The gonococcal strain R-10 is shown to contain two antigenically different R-type lipopolysaccharides: one of these has the same properties described for the gonococcal lipopolysaccharide, while the other does not have any cross-reaction with it. The latter was purified from a mutated colony able to express only one type of lipopolysaccharide. By inhibition enzyme-linked immunosorbent assay it was shown that the difference between the two lipopolysaccharides is located in the core region which, when purified and analyzed by gel filtration and gas liquid chromatography, did not show any difference either in size or in chemical composition, leading to the conclusion that the two cores must differ just in the structure of the antigenic determinant.